Utilization of bubble levels for archery bows is well known in the art. Many such levels in the prior art are either permanently installed without adjustment capability or semi-permanently installed and limited to adjustment in one axis only. Prior art attempts to correct errors occurring in the sight picture viewed by an archer when aiming uphill or downhill (a third axis rotation of the bow sight) have been imprecise and frequently require complex mechanisms that are cumbersome and complicated.
The third axis adjustment is necessary to compensate for errors in the relationship between the horizontal ground plane, the vertical plane of the bow, and the inclination of the bow as it is being fired.
It is possible for a prior art bubble level to be adjusted so that when the archer sights the bow before firing, the pin sight or other similar sight, accurately depicts where the arrow should strike when it reaches the target. However, if the target is raised above the horizon, or below the horizon, it is possible for the bubble level to falsely indicate that the plane of the bow needs to be canted with respect to horizontal. Under such circumstances, such canting results in an erroneous indication to the archer. When the archer subsequently corrects for what he views as the sight picture, the bow becomes canted with respect to horizontal. The result of such action is the arrow traveling to the right or left of the target since his “corrections” actually result in the arrow's path being directed to one or the other side of the target rather than directly at the target.